Prostate MRI: Access to and Current Practice of Prostate MRI in the United States

Purpose

MRI of the prostate has increasingly become more important in clinical medicine because of the risk of over-detection of low-grade, low-volume prostate cancer, as well as because of the poor sampling of transrectal ultrasound-guided prostate biopsy in high-risk patients. We sought to determine the access, imaging protocols, and indications for MRI imaging of the prostate in the United States.

Methods

A brief survey was sent through mailing lists to members of the Society of Abdominal Radiology and Texas Radiological Society.

Results

Thirty-six academic centers responded to the survey, 88.9% of which routinely perform prostate MRI. Nine centers routinely performed imaging at 1.5T with an endorectal coil (25%), 11 performed at 3.0T without an endorectal coil (31%), and 10 performed at 3.0T with an endorectal coil (28%). All institutions used T1-weighted axial and orthogonal T2-weighted sequences. Most groups used diffusion-weighted imaging (94.7%) and dynamic contrast enhancement (81.6%). Only 21.1% of groups performing prostate MRI routinely performed MR spectroscopy as part of their protocol.

Conclusions

Prostate MRI is becoming a commonly performed examination at academic institutions, with most locations performing prostate MRI at minimum standards. There is a need to educate nonacademic practices regarding the addition of functional MRI techniques to anatomic techniques, increase the number of institutions that regularly perform prostate MRI, and increase access to direct MRI-guided biopsy in institutions that perform prostate MRI on a regular basis.

Introduction

The American Cancer Society estimates that there will be 241,740 new cases of prostate cancer in 2012, ranking in incidence behind only skin cancer [1]. Although approximately 28,170 men will die of prostate cancer in 2012, an almost 100% 5-year survival can be achieved if diagnosis is made at an early stage [2]. Worldwide, MRI is increasingly performed in the diagnosis and staging of prostate cancer. Despite the growing utilization of prostate MRI, it is not a standard procedure performed at all institutions in the United States. There is also wide variability among the methods and protocols in which prostate MRI is performed. For example, in addition to standard MR T1- and T2-weighted imaging, dynamic contrast enhanced imaging (DCE), MR spectroscopy (MRS), and diffusion-weighted imaging (DWI) methods are frequently performed. There is extensive literature on the accuracy of these techniques [3, 4, 5, 6]. Debate is ongoing related to the MRI field strength and endorectal coil requirements for these studies [2, 6, 7, 8, 9, 10]. The initial indication for prostate MRI was for cancer staging and to evaluate the presence of extracapsular extension and seminal vesicle invasion [11]. The indications for prostate MRI have shifted towards searching for “missed tumors” in patients with prior negative biopsies, planning biopsy targeting, planning radiation, and selecting patients for active surveillance [3, 6].

Recently, the European Society of Urogenital Radiology (ESUR) developed prostate MRI recommendations based on consensus expert opinions, with minimal and optimal requirements [7, 8]. Unlike other imaging techniques in the United States, there is not a definitive and universal protocol for prostate MRI. Also, although best practice guidelines may exist, many practices throughout the United States may not follow this standard. This survey was undertaken to determine the access and practice of prostate MRI amongst academic, private practice, and community groups throughout the United States.